Fuel Pump: Description and Operation

Fuel Pump Description:

PURPOSE
To supply a constant pressurized flow of fuel for fuel injection operation. When the engine is turned off, the check valve maintains residual fuel pressure for easy starting.


OPERATION
When the engine is started, the main relay activates the pump. Fuel entering the inlet port flows inside the motor from the pumping chamber and is forced through the discharge port via the check valve. The check valve maintains residual pressure after pump shutdown so the fuel system stays pressurized even when the engine is not running. If fuel flow is obstructed at the discharge side of the fuel line, the relief valve will open to bypass the fuel to the inlet port and prevent excessive fuel pressure.


CONSTRUCTION
The fuel pump is comprised of a DC motor, a circumference flow pump, a relief valve for protecting the fuel line systems, a check valve for retaining residual pressure, an inlet port, and a discharge port. The pump assembly consists of the vane-type impeller (driven by the motor), the pump casing (which forms the pumping chamber), and the pump cover.